A vaporizer is a device used for vaporizing a liquid for the purpose of inhalation. It is well known that draw-over vaporizers can be used for both civilian and military anesthesia. The earliest vaporizer is an oxford miniature vaporizer which has been in service over 40 years.
Since an electronic cigarette was developed the vaporizer has become popular. The electronic cigarette is a battery-powered vaporizer which simulates tobacco smoking by producing a vapor that resembles smoke. In order to meet the needs of the electronic cigarettes many vaporizers have been designed and manufactured. Some of them can be described in the following US patents.
U.S. Pat. No. 8,742,974 discloses a vaporizer in which the heating device can be configured by fixing heater plates to cover the front, rear, left and right side surfaces and the upper and bottom surfaces of the chamber. The heater plate may be formed by, for example, incorporating a heater in a plate made of aluminum or copper, etc.
U.S. Pat. No. 8,739,786 discloses a portable hand-held vaporizer for electronic cigarette application. The heating element of the vaporizer is a tungsten-based metallic alloy in the form of a coil that is disposed at least partially within the airflow passage. In other embodiments, the heating element is made from nickel-chrome, other types of metals, or metal-based composites that have a generally low thermal resistivity and are generally safe to pass air through for human consumption. In further embodiments, the heating element may be in the form of a plate or other shape, and may be located within a piece of glass or in close proximity to the airflow passage, but yet still able to effectively transfer heat.
U.S. Pat. No. 8,757,147 discloses a personal vaporizer unit which comprises a first wick element and a second wick element having a porous ceramic. The first wick element is adapted to directly contact a liquid held in a reservoir. The reservoir may be contained by a cartridge that is removable from the personal vaporizer unit. A heating element is disposed through the second wick element. An air gap is defined between the first wick element and the second wick element with the heating element exposed to the air gap. Air enters the first wick element through a hole in a housing holding the first wick element.
U.S. Pat. No. 8,678,012 discloses a tobacco solution atomizing device for electronic cigarette which comprises a glass fiber tube, a glass fiber yarn, a heating coil, a cotton cloth layer and a synthetic fiber layer, wherein the glass fiber yarn is insert into the heating coil which is then located inside the glass fiber tube; the ends of the glass fiber silk and two wires which are used to electronically connect the heating coil to the positive and negative electrode connectors extends outward through the glass fiber tube; the cotton cloth layer enwraps the outside wall of the glass fiber tube and reveal ends of the glass fiber yarn are pressed tightly between the cotton cloth layer and the glass fiber tube; a synthetic fiber layer is filled within the annular shape space between the cotton cloth layer and the fixing sleeve for holding the tobacco solution.
It can be seen from the above described vaporizers that each vaporizer generally consists of a small heating element responsible for vaporizing e-liquid, as well as a wicking material that draws liquid in. Along with a battery, the vaporizer is the central component of every electronic cigarette. The vaporizer is assembled by putting together of all separately manufactured parts. Several disadvantages can be found with these vaporizers:                (1) Due to discrete parts, the design, commissioning and installation of the vaporizer is relatively complicated.        (2) Jointing and connecting of the discrete parts significantly reduce the reliability of the vaporizer.        (3) Power consumption is relatively high because the heater is not allowed to contact with the vaporized liquid directly.        (4) No temperature sensor for measuring the temperature of the heating element directly.        (5) Vaporized liquid amount cannot be controlled since no air flow sensor is used for measuring the air flow rate.        Therefore, a need exists to overcome the problems with the prior art as discussed above.        